From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7F9B0C433EF for ; Wed, 8 Dec 2021 11:08:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232103AbhLHLMQ (ORCPT ); Wed, 8 Dec 2021 06:12:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50382 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232078AbhLHLMO (ORCPT ); Wed, 8 Dec 2021 06:12:14 -0500 Received: from mail-pf1-x432.google.com (mail-pf1-x432.google.com [IPv6:2607:f8b0:4864:20::432]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 05557C061746 for ; Wed, 8 Dec 2021 03:08:43 -0800 (PST) Received: by mail-pf1-x432.google.com with SMTP id k26so2128548pfp.10 for ; Wed, 08 Dec 2021 03:08:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=74fcl84eMF3trMMN2JVz1x4AFBWc9HU1GFAGLmUM5eE=; b=VKlr4hE6P3/KVxbIhcLJDA0sF52nL0lnTLSlQue1EOi6nOPZmlq7+N6t34Z4nlAn6S 6NYswFiLZFVt72m7dLmKsXjcv49Tzn4Vfnpcat4WRibMq/7lLfmYUvxqlDrF2qI/vqdA 5aiicTqsTeo5rZI/iqEDgXPe0X06ShRim5daAufoj+27dBC6vjm3F6QWqdhhrBeccdlx vioUF/TKnCwOTAFHjtjXkA2ZHEBTUJBfBC9YS2QXCQak02LJEkZyHt3r3mxI7EG3xklk 0XSnYu5Z2L1fze0kQgB0lt62j14Jn3CZPbd5zi5beWbTOrpQnWraqlF9nD9BmgP3hxz8 xxDg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=74fcl84eMF3trMMN2JVz1x4AFBWc9HU1GFAGLmUM5eE=; b=yx0NqUKp1QeKqGOirE0FASlMt/WQ49qR23OG3klt3vCsTgcO41GNwBUmKqcU7Kbmjx JKLX5H+qabTOeltc5jU3uVmhT4LIT+f3kXf3IMZFnqFApkpP8t824NTt2Ag6K9Nukcw7 f5CdXSu7DnFY1bj/3or3Rlu0H7FVnd0a4PeGNt1d+l4/j9V9PTkag+DAz66rhRkLhvEL +KxjQFdVQPT49kDNjoNAAmMGNPiX+5TLu/iSyxVIdA/1EJvXEkzu1TslLe9rfyilx2oN Gb73FPECXpsf1ugTkUVpFxZmOz7Kl1+bLECt4NRurcx+Lj99P5OSCt8OH1+Q7+NvbZMW zLqQ== X-Gm-Message-State: AOAM532KdX5meCGviIANW2ME2UCJpHPtkDczEOxpLocXECmy9qtbzr+y onLrwj7txWUG0msqIq9x0rdhaBAimXI= X-Google-Smtp-Source: ABdhPJwdwD0NWVFtmrZKBdCkBw1nVwlMCHpLBoT9j05zLnwJyoppx7uciS4Kg9RdTDjqkCWrZh05WA== X-Received: by 2002:a63:e43:: with SMTP id 3mr29449478pgo.73.1638961722423; Wed, 08 Dec 2021 03:08:42 -0800 (PST) Received: from localhost ([47.251.3.230]) by smtp.gmail.com with ESMTPSA id a16sm2254924pgm.57.2021.12.08.03.08.41 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 08 Dec 2021 03:08:41 -0800 (PST) From: Lai Jiangshan To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, xen-devel@lists.xenproject.org, Lai Jiangshan , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" Subject: [PATCH 03/11] x86/entry: Switch the stack after error_entry() returns Date: Wed, 8 Dec 2021 19:08:25 +0800 Message-Id: <20211208110833.65366-4-jiangshanlai@gmail.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20211208110833.65366-1-jiangshanlai@gmail.com> References: <20211208110833.65366-1-jiangshanlai@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lai Jiangshan error_entry() calls sync_regs() to settle/copy the pt_regs and switches the stack directly after sync_regs(). But error_entry() itself is also a function call, the switching has to handle the return address of it together, which causes the work complicated and tangly. Switching to the stack after error_entry() makes the code simpler and intuitive. Signed-off-by: Lai Jiangshan --- arch/x86/entry/entry_64.S | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index f8faff3ca61e..6baa7413f7eb 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -323,6 +323,8 @@ SYM_CODE_END(ret_from_fork) .macro idtentry_body cfunc has_error_code:req call error_entry + movq %rax, %rsp /* switch stack settled by sync_regs() */ + ENCODE_FRAME_POINTER UNWIND_HINT_REGS movq %rsp, %rdi /* pt_regs pointer into 1st argument*/ @@ -981,14 +983,10 @@ SYM_CODE_START_LOCAL(error_entry) /* We have user CR3. Change to kernel CR3. */ SWITCH_TO_KERNEL_CR3 scratch_reg=%rax + leaq 8(%rsp), %rdi /* arg0 = pt_regs pointer */ .Lerror_entry_from_usermode_after_swapgs: /* Put us onto the real thread stack. */ - popq %r12 /* save return addr in %12 */ - movq %rsp, %rdi /* arg0 = pt_regs pointer */ call sync_regs - movq %rax, %rsp /* switch stack */ - ENCODE_FRAME_POINTER - pushq %r12 ret /* @@ -1020,6 +1018,7 @@ SYM_CODE_START_LOCAL(error_entry) */ .Lerror_entry_done_lfence: FENCE_SWAPGS_KERNEL_ENTRY + leaq 8(%rsp), %rax /* return pt_regs pointer */ ret .Lbstep_iret: @@ -1040,12 +1039,9 @@ SYM_CODE_START_LOCAL(error_entry) * Pretend that the exception came from user mode: set up pt_regs * as if we faulted immediately after IRET. */ - popq %r12 /* save return addr in %12 */ - movq %rsp, %rdi /* arg0 = pt_regs pointer */ + leaq 8(%rsp), %rdi /* arg0 = pt_regs pointer */ call fixup_bad_iret - mov %rax, %rsp - ENCODE_FRAME_POINTER - pushq %r12 + mov %rax, %rdi jmp .Lerror_entry_from_usermode_after_swapgs SYM_CODE_END(error_entry) -- 2.19.1.6.gb485710b